Self-healing polyacrylates based on dynamic disulfide and quadruple hydrogen bonds.

Herein, a self-healing polyacrylate system was successfully prepared by introducing crosslinking agents containing disulfide bonds and monomers capable of forming quadruple hydrogen bonds through free radical copolymerization. This polymer material exhibited good toughness and self-healing properties through chemical and physical dual dynamic networks while maintaining excellent mechanical properties, which expanded the development path of self-healing acrylate materials. Compared to uncrosslinked and single dynamically crosslinked polymers, its elongation at break was as high as 437%, and its tensile strength was 5.48 MPa. Due to the presence of dual reversible dynamic bonds in the copolymer system, good self-healing was also achieved at 60 °C. In addition, differential scanning calorimetry and thermogravimetric analysis measurements confirmed that the thermal stability and glass transition temperature of the material were improved owing to the presence of physical and chemical cross-linking networks.

Single-Cell Sensitive Colorimetric pH Detection Based on Microscope Ratiometric Grayscale.

Rapid and accurate identification of the intracellular pH is critical in the field of biomedicine. In this work, we effectively identified and quantified the intracellular pH and its distribution at the single-cell level using an image sensor based on an ordinary bright-field optical microscope that divided the cell staining images into their red (R) and blue (B) channels. The grayscale of the R and B channels was subjected to a ratiometric operation to generate ratiometric grayscale cell images of the microscope. A standard curve of pH against ratiometric grayscale curve was then obtained by incubating HeLa cells at pH 6.00-7.60 in a high concentration K+ ion buffer solution containing nigericin for obtaining certain intracellular pH values. A good correlation was evidenced between pH and the ratiometric grayscale of the R and B channels in the pH range of 6.00-7.60. Subsequently, the intracellular pH value of the A549 cells under the experimental conditions was measured to be 7.22 ± 0.01 by the method. Furthermore, the changes in the intracellular pH of HeLa cells stimulated with hydrogen peroxide were sensitively monitored, which demonstrated the applicability of the method. Due to its ease of use, the developed colorimetric microscopy pH detection and monitoring method provide prospects for pH-related single-cell studies.

Morphological Characteristics, Ultrastructure, and Chemical Constituents of the Endotesta in Ginkgo (Ginkgo biloba L.).

Ginkgo biloba L. is a tree species of significant economic and ecological importance. Prior studies of the Ginkgo biloba seed coat have predominantly focused on the sarcotesta and sclerotesta, with less attention paid to the endotesta. In this study, the development and formation of Ginkgo endotesta were examined using light microscopy and transmission electron microscopy. The structural properties of the mature endotesta were analyzed using micro-CT imaging and scanning electron microscopy. The results indicate that the endotesta possess a membranous structure primarily originating from the inner bead peridium, a segment of bead core tissue, and the macrospore membrane. The endotesta from the middle constriction line to the chalazal end comprises a single layer with a greyish-white papery structure. In contrast, the endotesta was divided into two inner and two outer layers, from the middle constriction line to the micropylar end. The outer endosperm adheres closely to the sclerotesta, while the inner endosperm adheres to the seed kernel. The surface of the endotesta was irregularly raised, with thicker wax at the chalazal end, whereas the micropylar end demonstrated similar characteristics with thinner wax and tumor layers. The endotesta contained 17 amino acids, 18 fatty acids, 10 trace elements, and 7 vitamins. Overall, its nutritional value was relatively well balanced.